My guess it that spelling it “cue” would suggest it ought to be pronounced like “k” + “u” … so “cue” is the wrong spelling for that pronunciation.

“ce” doesn’t work because that’s a soft “c” pronounced like “se”.

“que” almost works but it’s a short “euh”, and also “que” is already used for a different word.

So to make it a long “euh” after “qu”, it’s “qu”+”eu”.

But it’s feminine (perhaps because Latin “cauda” from which it’s derived is feminine), hence the terminal “e” i.e. “qu”+”eu”+”e”.

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There’s an interesting Wikipedia article on the history of French spelling.

Based on that, if I recall correctly, “Old French” was spelled more-or-less according to how it was pronounced; but pronunciation (and spelling) varied from region to region.

There were later/subsequent deliberate/scholarly efforts to ensure that:

• Spelling matches pronunciation
• Spelling rules are more-or-less consistent
• Spelling (e.g. silent latters) help to suggest words’ Latin etymologies

So it’s not impossible that “cue” was a natural spelling, and became “queue” as a more precise spelling.

According to the OED cue, where it means either a plait of hair, or a billiard cue, is just a variant spelling of the French queue, which means tail.

Where cue means a prompt given in the theatre, that particular use of the word has an unknown etymology.

French queue comes from Latin coda (also spelled cauda) which designated the appendage that prolongs the spinal column. It was spelled cue, coe or even keue in Old French and only started being spelled queue in the 12th century. Spelling was no fixed in those days.

The English borrowed the word after the French had adopted the present spelling *queue, first to mean a “long roll or plait of hair worn hanging down behind like a tail” and later the billiard stick. I gather the Old French spelling is just a coincidence and that the English spelling is a restitution of the word. What’s interesting is that in English both spellings, “queue” and “cue” coexist.

Anglo-Norman origins

Usually, this is attributed to the 12th century anglo-norman Chanson de Roland (text; easy text):

CXIV
[1488]Li arcevesque cumencet la bataille.
Siet el cheval qu’il tolit a Grossaille,
Ço ert uns reis qu’l ocist en Denemarche.
Li destrers est e curanz e aates,
Piez ad copiez e les gambes ad plates,
Curte la quisse e la crupe bien large,
Lungs les costez e l’eschine ad ben halte,
Blanche la cue e la crignete jalne

Petites les oreilles, la teste tute falve;
Beste nen est nule ki encontre lui alge.
Li arcevesque brochet par tant grant vasselage:
Ne laisserat qu’Abisme nen asaillet;
Vait le ferir en l’escut amiracle:
[…]

Latin

So this cue comes from the Latin cauda/coda. This is most probably pronunced like a k. The two forms sound basically like kao-da vs. koda with some variation. In latin words beginning with the letter q are quite common I think, and mostly always followed with u. The pronunciation may(kw) or may not be different. What I imagine is they saw that and have some Scandinavian, Norman influences, so did they have some natural cue about that pronunciation? Or did they just try to copy it, especially if Latin was well perceived a language or historically relevant to some? Furthermore, maybe you have something akin to a preposition such as de, and then you would have had something like a koede de cheval for ponytail, which would be really aggravating. If you were to drop or shorten the last syllable, you would be left with cau/co; so how does a Norman language deal with that?? I speculate they must have transliterated it from Latin directly and dropped the last part, and eventually that was rejected – in French. It seems in Norman quisse was how cuisse is prononced today in French, so it’s that kw sound, very much like qu in latin I suspect, again. You can’t make queue with cue phonetically in French unless you were to rely on something else…

Systematic construction

In the Historical section of this article in the Littré on queue, you see the Chanson example, then followed by examples with cöe(see also Trésor). Right away cue is gone, and it’s now coe, a bit like coeur but without the last sound? Maybe that would have been slightly confusing? And ultimately what about cueillir, recueuil etc…. it becomes a bit crowded. So listen again to the Chanson: Rolans sis niez me coillit en haür. This “cueillir” is also quite different from modern French. So surely it was adapted for something that sounded different. And then all this disappears in the 15th. So it seems like it was idiomatic or somehow just worked phonetically in English, but didn’t compute with what French was becoming in the 15th.

Norman influence(s) and Old French generally

Normal language&history

Aside from the political influence Normandy exerted at a specific period in time, there is also value in briefly stating the historical context where the Norman language expresses itself initially:

Les nouveaux venus[anglo-scandinavian settlers, so maybe also this] vont exercer sur la langue vernaculaire une
influence limitée de substrat, notamment sur le vocabulaire (200 mots
tout au plus, issus du norrois ou du vieil anglais cf. tableau I) et
de manière plus anecdotique sur la phonétique.

This is just to show that generally some influences can carry other interferences over and that the ensuing result varies; how language changes may not be something linear or grounded on a specific mission; there might be opportunity, randomness, normative instruments, and of course history.

Old French

From the wikipedia article:

[…] si l’ancien français s’écrit presque comme il se prononce, les
graphies deviennent très vite archaïsantes. Par exemple, doté de
nombreuses diphtongues, il les représente directement : /eu/ se lit
donc [ew] et /oi/ [oj]. Mais les graphies restent figées alors que la
prononciation continue d’évoluer: /eu/ vaut [ew] au XIe siècle mais
[œu] au XIIe siècle et [œ] à partir du XIIIe siècle sans que la
graphie ne change réellement. […]

En conclusion, il convient de comprendre que l’ancien français possède
une orthographe quasi-phonétique pratiquée avec un alphabet qui ne s’y
prête pas forcément, ce qui explique l’abondance de graphies
parallèles et les diverses solutions plus ou moins efficaces, tels les
digrammes, mais, surtout, dès que les prémices de l’orthographe, au
sens actuel, font leur apparition : l’écriture est en retard sur la
prononciation mais permet, par l’adoption de conventions, une
meilleure reconnaissance des constituants des mots.

Synthèse […] la lecture des diphtongues graphiques est complexe car les diphtongues prononcées ont évolué beaucoup plus vite que la
graphie. On pourra retenir comme règle de lecture acceptable que les
diphtongues se sont monophtonguées après le XIIe siècle (passant soit
à une combinaison semi-consonne + voyelle soit à une voyelle seule.
Retenir aussi que oi se lit /we/ ou /wɛ/ et ue comme eu /œ/ ou /ø/ ;

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A. So was there ever a motivation to make words more “straightforward” etc?¹ I just think the French language asserted herself, in time, to find solutions on its own terms so to speak, so that the “system” would work. And then at some point in the 15th it stabilized in some respects, like explained in this Q&As, with indeed less reliance in this very case on that original latin anglo-norman construction for cue.

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_{1. Take the word hue in English which is shorter than color, and from the same era; yet the latter is what is casually used today(maybe that’s a ticket for a Q. on ELU.).}

what about from hebrew root qawah? meaning to wait
There are forms where the first vowel is /i/ or /I/.

"My guess it that spelling it "cue" would suggest it ought to be pronounced like "k" + "u" … so "cue" is the wrong spelling for that pronunciation."

not at all. queue has the same pronunciation as cue

but it does not sound like kyu, it sounds like keu

Edit: I corrected some mistakes as kindly pointed out by @Eauquidort.

Disclaimer: I’m not an expert on the subject, and the following is just my guess.

I would like to offer a phonological prospective of the question. Apparently, the word has undergone the following changes:

Latin cauda > Latin cōda > Old French coe /kɔə/ > Modern French queue /kø/

1. Latin diphthong /aw/ reduces to /ɔ/.
2. /d/ deletes by lenition, as is usual in French: [d] > [ð] > zero.
3. Word-final /a/ becomes [ə] in Old French. Note that word-final e was pronounced [ə] in Old French; it became silent on its way to Modern French.
4. A stressed /ɔ/ evolves as follows in French: /ɔ/ > /wɔ/ > /wɛ/ > /ø/, which was spelled eu.

Thus one expects the result to be spelled *ceue. If this were the case, then according to general phonological patterns, c before a front vowel (pronounced /k/ in Latin) would palatize and undergo the following changes: /k/ > /tʃ/ > /ts/ > /s/. This did not happen for queue, and it was reflected in the spelling: c was replaced by qu. In fact, the evolution /ɔ/ > /wɔ/ protected the /k/ from palatalization.

My guess is that this happened to all such c to prevent it from palatalizing. Another example is the word qui, where the /k/ did not palatalize to /s/ as usual. Somehow /k/ spelled as qu is immune to palatalizing and other phonological changes, but I’m not sure why.

Another piece of evidence from Le Petit Robert:

La forme ancienne coue, usitée jusqu’au début du XVIIe siècle, se retrouve dans les dérivés couette et couard.

Here /ɔ/ avoided fronting into /ø/, hence the spelling c is retained.

In modern French spelling, "ue" and "eue" generally represent different sounds, so "cue", which looks like it should be pronounced /ky/, does not work very well in modern French as a simplified spelling of "queue" /kø/ (it does work in English, of course, where queue and cue are both pronounced /kju/).

In Old French, there was more variability in spelling. The Old French letter "u" could correspond to either the high front rounded vowel sound [y] (as in modern French; this vowel was the outcome of Latin long /uː/) or to another vowel that was either pronounced [u] (as in modern French "ou") or possibly in some cases as a diphthong [ou]; this latter vowel was the outcome of Latin long /oː/ or short /u/, and could also be spelled "o" or "ou". In later stages of Old French, this latter vowel came to be spelled "eu", thought to represent a diphthong [eu], when it occurred in stressed syllables not ending in a consonant.

The use of "u" with the value /u/ seems to have been very common in unstressed syllables, but it seems to have also been possible in stressed syllables sometimes, as in the Old French spelling urs for modern French ours (from latin ursus) and the very similar example of rue (also roe, rohe, ruee, roee) for modern French roue (from Latin rōta). (The TLFi notes that "reue" would be the regular outcome of rōta.)

I think the [u], [ou] or [eu] vowel is what is represented by the u in the spelling cue, the o in the spelling coe, and the eu in the spelling keue and modern French queue.

As mentioned above, this vowel sound came from Latin /oː/. The Latin ancestor of queue has the form cōda [koːda]. This is a variant of the Latin word cauda [kauda]. The replacement of the diphthong [au] with the long vowel [oː] is thought to have been a feature of some "rustic" accents of Latin that affected the form of a few words in the Romance languages. For most words, Romance languages show the outcome of Latin [au] (which sometimes developed to an [o] vowel by later sound changes that were different from the "rustic" monophthongization seen in the history of this word).

In the history of French, "k" came to not be used regularly, and instead was replaced with "qu" before the letters "i" and "e". So that’s how you get queue.